Patients with asthma who are severely symptomatic should undergo ECG monitoring, as with any seriously ill patient. Sinus tachycardia and ECG evidence of right heart strain are common in patients with acute asthma. The use of beta2-agonist therapy will cause a paradoxical decrease in heart rate as pulmonary function improves and symptoms are relieved. Supraventricular tachycardia raises the consideration of theophylline toxicity. Arrhythmias other than supraventricular tachycardia are rare.
Bronchoprovocation testing with either methacholine or histamine is useful when spirometry findings are normal or near normal, especially in patients with intermittent or exercise-induced asthma symptoms. Bronchoprovocation testing helps determine if airway hyperreactivity is present, and a negative test result usually excludes the diagnosis of asthma.
Allergen-inhalation challenges can be performed in selected patients but are generally not needed or recommended. This test requires an available allergen solution and specialized centers able to handle potentially significant reactions. A negative test finding may allow continued exposure to an allergen (eg, family pet); a positive test finding can dramatically indicate that the patient should avoid a particular allergen. This test is often needed to help diagnose occupational asthma.
Aside from cardiovascular applications, MRI of the thorax is used primarily as a problem-solving modality in the workup of patients with lung, mediastinal, or pleural lesions. MRI is a useful alternative to CT pulmonary angiography in evaluating possible pulmonary embolic disease in patients in whom iodinated contrast agent cannot be administered and when the avoidance of ionizing radiation is preferred.
Learn more about the workup of asthma patients.
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Cite this: Zab Mosenifar. Fast Five Quiz: Challenges of Severe Asthma - Medscape - Feb 25, 2021.